Hub Cover Assembly Thermal Buffer for Gas Turbine Exhaust
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Solution Overview
Problem
In heavy-duty gas turbine engines, the mismatch in thermal expansion between neighboring components can lead to stress, cracks, deformation, or leakage in the exhaust gas housing, particularly affecting the sealing function of the hub cover and potentially damaging the bearings.
Innovation Solution
A hub cover assembly comprising an adapter ring with wedges, a spacer ring structure, and an external cover, which forms a sealed cylindrical chamber to buffer temperature differences and reduce mechanical stress, while the wedges aid in insertion and centering of the adapter ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover is directly exposed to hot gas to seal the exhaust hub, then sealing function is improved, but thermal stress and leakage increase due to temperature difference
Solution Approach 1:
The patent introduces an intermediate temperature chamber between the hot gas flow path and the exhaust hub rear end. This chamber acts as a thermal buffer, with its forward end exposed to hot gas and its rear end sealing the exhaust hub. The intermediate chamber reduces the temperature differential across the seal, thereby decreasing thermal stress and preventing leakage while maintaining sealing reliability.
2Temperature
If special materials are used for the cover, then temperature resistance is improved, but cost and complexity increase
Solution Approach 1:
The patent divides the cover structure into multiple segments: the intermediate temperature chamber, the adapter ring, and the seal assembly. This segmentation allows each component to be optimized for its specific thermal environment rather than requiring the entire cover to withstand extreme temperatures. Standard materials can be used in lower-temperature zones, reducing overall complexity and cost.
3Strength
If the exhaust hub is enclosed in a casing, then protection is improved, but thermal expansion mismatch causes deformation and cracks
Solution Approach 1:
The patent changes the thermal parameters within the exhaust hub enclosure by introducing the intermediate temperature chamber. This creates a temperature gradient that reduces the thermal expansion differential between neighboring components. The adapter ring with its specific geometric parameters further accommodates thermal expansion while maintaining structural integrity, preventing deformation and cracks.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hub cover assembly effectively reduces the risk of damage from extreme temperatures by maintaining an intermediate temperature between the hot gas flow path and the exhaust hub, thereby minimizing mechanical stress and leakage.
Implementation Method 1
the spacer ring structure and the external cover sealingly delimit a cylindrical chamber laterally and axially on one side... serves as a temperature buffer that reduces the mechanical stress caused by different thermal expansion
Implementation Method 2
the adapter ring comprises a plurality of wedges arranged at a same distance from a center of the adapter ring and projecting axially in a direction opposite to the spacer ring structure
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A hub cover assembly for an exhaust hub of a heavy-duty gas turbine engine, includes an adapter ring (21), configured to be coaxially fitted to a rear end (11a) of an exhaust hub (11) of a heavy-duty gas turbine engine; a spacer ring structure (22), having a first axial end removably and sealingly connectable to the adapter ring (21); and an external cover (25) applied to a second axial end of the spacer ring structure (22), whereby the spacer ring structure (22) and the external cover (25) sealingly delimit a cylindrical chamber (28) laterally and axially on one side.